U.S. patent application number 13/370631 was filed with the patent office on 2012-08-23 for measuring device mounting method and structure.
This patent application is currently assigned to TRW Automotive U.S. LLC. Invention is credited to Mike Babala, Carl A. Munch, Michael F. O'Connor, Paul Zatyko.
Application Number | 20120210787 13/370631 |
Document ID | / |
Family ID | 46651576 |
Filed Date | 2012-08-23 |
United States Patent
Application |
20120210787 |
Kind Code |
A1 |
Babala; Mike ; et
al. |
August 23, 2012 |
MEASURING DEVICE MOUNTING METHOD AND STRUCTURE
Abstract
A measurement device (10) mounting arrangement includes a
support member (30) and a sensing device (12) in a circuit housing
(22). The circuit housing (22) is electrically and mechanically
connected to the support member (30) through a mounting structure
(32). The circuit housing (22) has a resonance frequency and the
sensing device (12) has an operational resonance frequency. The
sensing device (12) measures a physical parameter and provides a
signal indicative thereof. An under-fill material (40) is located
between the support member (30) and the circuit housing (22) for
shifting the resonance frequency of the circuit housing (22) away
from the operational resonance frequency of the sensing device
(12).
Inventors: |
Babala; Mike; (Plymouth,
MI) ; Munch; Carl A.; (Troy, MI) ; Zatyko;
Paul; (Westland, MI) ; O'Connor; Michael F.;
(Troy, MI) |
Assignee: |
TRW Automotive U.S. LLC
|
Family ID: |
46651576 |
Appl. No.: |
13/370631 |
Filed: |
February 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61445311 |
Feb 22, 2011 |
|
|
|
Current U.S.
Class: |
73/504.12 ;
156/91 |
Current CPC
Class: |
G01C 19/5783
20130101 |
Class at
Publication: |
73/504.12 ;
156/91 |
International
Class: |
G01P 15/08 20060101
G01P015/08; B32B 37/12 20060101 B32B037/12; B32B 37/02 20060101
B32B037/02 |
Claims
1. A measurement device mounting arrangement comprising: a support
member; a sensing device in a circuit housing and electrically and
mechanically connected to said support member through a mounting
structure, the circuit housing having a resonance frequency and the
sensing device having an operational resonance frequency, the
sensing device measuring a physical parameter and providing a
signal indicative thereof; and an under-fill material located
between said support member and said circuit housing for shifting
the resonance frequency of the circuit housing away from the
operational resonance frequency of the sensing device.
2. The measurement device mounting arrangement of claim 1 wherein
said under-fill material is a non-conductive material selected from
the group comprising a gel adhesive, epoxy, silicon, rubber, and
acrylic.
3. The measurement device mounting arrangement of claim 1 wherein
said sensing circuit is a MEMS gyro.
4. The measurement device mounting arrangement of claim 3 wherein
said MEMS gyro includes a Coriolis sensor that measures angular
rate about an axis of sensitivity.
5. A method for mounting a measurement device comprising the steps
of: electrically and mechanically securing a sensing device in a
circuit housing to a support member through a mounting structure,
the circuit housing having a resonance frequency and the sensing
device having an operational resonance frequency, the sensing
device measuring a physical parameter and providing a signal
indicative thereof; and locating an under-fill material between the
support member and the circuit housing for shifting the resonance
frequency of the circuit housing away from the operational
resonance frequency of the sensing device.
6. The method for mounting a measurement device of claim 5 wherein
said step of locating an under-fill material includes the step of
selecting the under-fill material from the group comprising a gel
adhesive, epoxy, silicon, rubber, and acrylic.
Description
RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional
Patent Application No. 61/445,311, filed Feb. 22, 2011, the subject
matter, which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention is directed to a measuring device
mounting method and structure and is more particularly directed to
a measuring device mounting method and structure wherein the
measuring device includes a resonant circuit.
BACKGROUND OF THE INVENTION
[0003] Measuring devices for sensing vehicle dynamics are known.
One particular type measuring device includes an inertial type
sensor that can be used for sensing a vehicle roll-over event.
Certain sensors for sensing a vehicle roll-over event use gyro(s)
to measure an angular rate of rotation about an associated axis of
sensitivity. In the era of miniaturization, such inertial sensors
that include gyros have been developed using microelectromechanical
("MEMS") technology.
[0004] A particular type of MEMS gyro operates on the Coriolis
principle, i.e., measuring an apparent deflection force on a moving
object as viewed from a rotating reference frame. Coriolis MEMS
gyros include an oscillating member having a resonant operating
frequency. Coriolis MEMS gyros can be manufacture as part of a
circuit package that is mounted to a printed circuit board ("PCB")
via a lead frame structure, i.e., wire leads are connected between
the circuit package and the PCB providing both electrical and
mechanical connection. The PCB may also carry other processing and
support circuitry for the MEMS gyro. The PCB with the MEMS gyro is
mounted in a known orientation in the vehicle (maybe in a separate
housing structure containing other circuitry/sensors) for the
measurement of particular vehicle dynamic events such as a vehicle
roll-over.
[0005] U.S. Pat. No. 7,087,994 appears to show a component mounting
arrangement with a support member using an under-fill material to
enhance mechanical bonding between the component and the PCB to
which the component is mounted. The under-fill material appears to
help distribute stress on the component and the electrical
connectors, and increase structural integrity. The under-fill
material may also help degradation from contaminants such as
moisture.
[0006] U.S. Patent Application Publication No. 2009/0308157A1
appears to show an integrated inertial measurement system and
methods using an epoxy under-fill applied to the periphery of a
circuit card assembly to securely fasten the circuit card assembly
to a base structure so that the circuit card assembly can withstand
high inertial loads.
SUMMARY OF THE INVENTION
[0007] The present invention provides a measuring device mounting
method and structure that includes an under-fill material to shift
the resonant frequency of the measuring device housing away from
its operating resonant frequency.
[0008] In accordance with one example embodiment of the present
invention, a measurement device mounting arrangement includes a
support member and a sensing device in a circuit housing. The
circuit housing is electrically and mechanically connected to the
support member through a mounting structure. The circuit housing
has a resonance frequency and the sensing device has an operational
resonance frequency. The sensing device measures a physical
parameter and provides a signal indicative thereof. An under-fill
material is located between the support member and the circuit
housing for shifting the resonance frequency of the circuit housing
away from the operational resonance frequency of the sensing
device.
[0009] In accordance with another example embodiment of the present
invention, a method is provided for mounting a measurement device
comprising the steps of electrically and mechanically securing a
sensing device in a circuit housing to a support member through a
mounting structure, the circuit housing having a resonance
frequency and the sensing device having an operational resonance
frequency, the sensing device measuring a physical parameter and
providing a signal indicative thereof, and locating an under-fill
material between the support member and the circuit housing for
shifting the resonance frequency of the circuit housing away from
the operational resonance frequency of the sensing device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The foregoing and other features and advantages of the
present invention will become apparent to those skilled in the art
to which the present invention relates upon reading the following
description with reference to the accompanying drawings, in
which:
[0011] FIG. 1 is a schematic block diagram of a measurement device
mounted to a printed circuit board in accordance with an example
embodiment of the present invention;
[0012] FIG. 2 is a side cross-sectional view of the measurement
device and printed circuit board of FIG. 1 showing further mounting
details; and
[0013] FIG. 3 is a graphical representation showing a frequency
shift experienced by the housing for the measurement device as a
result of the present invention.
DETAILED DESCRIPTION
[0014] Referring to FIGS. 1 and 2, a measurement device 10 is
provided for sensing a vehicle operating condition. For example,
the measurement device 10 may be an inertial measuring device such
as a gyro 12 that senses changes in angular movement (e.g., angular
rate) and provides an electrical output signal indicative thereof.
One particular type of gyro 12 contemplated is a
microelectromechanical ("MEMS") gyro that operates on the Coriolis
principle. Such a gyro 12 includes a moving mass 14 that has a
resonant frequency. During rotational movement of the sensor,
forces against the moving mass 14, as viewed from a rotating
reference, are experienced by the moving mass 14. An electrical
signal is provided indicative of the sensed rotational forces.
[0015] Specifically, the moving mass 14 of the gyro 12 moves
back-and-forth along an axis 16 under a drive force as
schematically represented by springs 18. A force sensor 20, such as
a capacitive sensor, senses force experienced by the moving mass 14
in a direction perpendicular to the axis 16 as would occur if the
measurement device 10 were subjected to rotation, i.e., the
Coriolis force.
[0016] The measurement device 10 may be manufactured using MEMS
technology and mounted in a circuit housing (e.g., a chip package)
22. As part of the measurement device 10, processing circuitry 24
may be located within the circuit housing 22 for processing
electrical signals from the force sensor 20 and providing an output
signal indicative of the sensed rotational forces experienced by
the measurement device 10.
[0017] The measurement device 10 is mounted to a PCB 30 and is
electrically connected to other circuitry on the PCB 30 via
lead-frame wires 32. The lead-frame wires 32 provide both an
electrical connection and a mechanical connection between the
measurement device 10 and the PCB 30. The effective mechanical
connection provided by the lead-frame wires 32 and the PCB 30 is
schematically shown as springs 34 in FIG. 1.
[0018] The PCB 30 may carry other processing circuitry for further
processing of the output signal from the measurement device 10. The
PCB 30 is mounted to the vehicle 38 at an appropriate location so
as to measure a vehicle event such as a vehicle roll-over
event.
[0019] It has been discovered by the present applicants that during
vehicle operation, vibrations experienced by the vehicle 38 are
transferred to the PCB 30 and, in turn, to the measurement device
10 through the lead-frame 32. It has further been discovered that
circuit housing 22 of the measurement device 10, through the
lead-frame connection 32, has a resonant frequency. A problem can
occur if the resonant frequency of the circuit housing 22 is close
to the resonant operating frequency of the moving mass 14 of the
measurement device 10. In accordance with an embodiment of the
present invention, a process and structure are provided to shift
the resonant frequency of the circuit housing 22 away from the
resonant frequency of the moving mass 14 of the measurement device
10 to attenuate vibration affects.
[0020] In accordance with the present invention, an under-fill
material 40 is operatively located between and in contact with the
PCB 30 and the circuit housing 22. The under-fill material 40 could
include a variety of possible materials including gel adhesive,
epoxy, silicon, rubber, and/or acrylic or any other non-conductive
material that would provide desired results in accordance with the
present invention. The under-fill material 40 functions as a damper
(schematically shown as dampers in FIG. 1) and has the effect of
shifting the resonant frequency of the circuit housing 22. The
amount of the under-fill material, the amount of the area of
contact between the PCB 30 and the circuit housing 22 by the
under-fill material, and/or the composition of the under-fill
material itself can be selected so as to control the amount and
direction of the resonant frequency shift of the circuit housing 22
away from the operational resonant frequency of the measuring
device 10.
[0021] Referring to FIG. 3, the resonant frequency 50 of the moving
mass 14 of the measurement device 10 is shown. Also, the resonant
frequency 52 of the circuit housing 22 absent any under-fill
material is shown. As can be seen, the values of the resonant
frequency values 50 and 52 are near each other. The resonant
frequency 54 shown is that of the circuit housing 22 when
under-fill material 40 is operatively positioned between the PCB 30
and the circuit housing 22. As mentioned, the amount of under-fill
material, the amount and pattern of contact of the under-fill with
the PCB 30 and the circuit housing 22, and/or the composition of
the under-fill material 40 are selected to control the amount of
the frequency shift.
[0022] With the frequency shift provided by the present invention,
vibrations experienced by the vehicle 38 and passed to the
measurement device 10 will have an attenuated effect on the
measurement value.
[0023] From the above description of the invention, those skilled
in the art will perceive improvements, changes and modifications.
Such improvements, changes and modifications within the skill of
the art are intended to be covered by the appended claims.
* * * * *